Direct numerical control (DNC) system including one high-speed data processing unit for each NC machine tool

ABSTRACT

High-speed data processing units are interposed on one-to-one basis between a host computer and each of NC units corresponding to each of NC machine tools. Each of the high-speed data processing units converts data transmitted from the host computer to each of the NC machine tools into NC data, and then inputs the data to each of the NC units, thereby making unnecessary for the NC units and the host computer to convert the data into NC data. Further, each of the high-speed data processing units temporarily stores machining data or the like transmitted from the host computer, thereby enabling each of machine tool bodies to continue its machining operation without being disturbed by the timing of data transmission.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a DNC (Direct Numerical Control)system, and in particular, to improvement of a DNC system for diemachining.

2. Description of the Related Art

There is a known DNC system having the structure in which a plurality ofNC machine tools are connected to one host computer, and NC data isdirectly transmitted from the host computer to the NC machine tools.Such a system is often applied in performing a complicated diesinkingoperation requiring mass NC data, or other operations.

However, in the conventional DNC system, a LAN (Local Area Network)system has been directly connected between the host computer and the NCmachine tools. For this reason, it is necessary for the host computer toexecute all the processings such as converting different-format data(setup or housekeeping data) required for changing a setup into NC data,transmitting the converted setup data and NC data for machining, or thelike. Particularly, during the complicated diesinking operation,excessive load is put on the host computer, as a consequence, theretends to be an interference in the data transmission to the NC machinetools. Further, If the NC machine tools perform part of the process tobe executed by the host computer, for example, a process for convertingdifferent format data for changing the setup into NC data, load on theside of the NC machine tool increases, which causes the processing speedto drop. For this reason, sometimes there is the need of restricting thedata transmission from the host computer to the NC machine tools.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a DNC system which iscapable of solving the problems raised in the prior art described above,and of efficiently operating each unit at a high speed without causingexcessive load on NC machine tools and the host computer.

To achieve the above object the present invention provides a DNC systemwhich controls a plurality of NC machine tools connected to one hostcomputer, including a high-speed data processing unit for each of theplurality of the NC machine tools so that command informationtransmitted from the host computer can be distributed to each of the NCmachine tools through each of the high-speed data processing units.

Preferably, each of the high-speed data processing units converts thedata which is not of NC data format out of the command informationtransmitted from the host computer into NC data, and inputs theconverted data to the corresponding NC unit of the NC machine tools.

Preferably, one of the NC machine tools is specified for andtransmitting the data required for changing the setup for machining tothe high-speed data processing unit corresponding to the specified NCmachine tool by using data input means connected to the host computer,and the NC data for machining read out of memory of the host computer istransmitted by the data input means. On the other hand, the high-speedprocessing unit determines whether the data transmitted from the hostcomputer is data required for changing a setup or machining data. If thedata is one required for changing a setup, the processing unit convertsthe data into NC data for a numerical control, and transmits theconverted NC data to the NC unit of NC machine tool corresponding to thehigh-speed data processing unit. If the transmitted data is machiningdata composed of NC data, the processing unit transmits it to the NCunit as it is.

Preferably, one of the NC machine tools is specified, and only machiningdata for one process and data for the next process required for changinga setup in operation schedule of the specified NC machine tool are set,thereby transmitting these data to the high-speed data processing unitcorresponding to the specified NC machine tool and storing them therein.On the other hand, when the high-speed data processing unit receives themachining data for one process and data required for changing the setupfor next process, the processing unit converts the data required forchanging the setup into NC data, and, if necessary, temporarily storesthe converted data and the machining data in its memory, and transmitsthese data to the NC unit of NC machine tool corresponding to thehigh-speed data processing unit.

Preferably, while the machining is being executed according to themachining data for one process transmitted to the NC machine tool, orthe setup operation for next process is being executed, the hostcomputer sets machining data for the next one process and data requiredfor changing a setup for initiating the next one process, and thentransmits these data to the high-speed data processing unit.

Further preferably, one of the NC machine tools is specified, and themachining data for all processes of operation schedule of the specifiedNC machine tool out of the whole schedule to be covered by the specifiedNC machine tool out of the whole schedule are set, thus transmitting andstoring these data to and in memory of the high-speed data processingunit corresponding to the specified NC machine tool. On the other hand,when one of the high-speed data processing units receives the machiningdata for the entire process and data required for changing a setup, theprocessing unit converts the data required for changing the setup intoNC data, and stores these data in its memory, thereby sequentiallytransmitting the stored data to memory of the NC unit corresponding tothe specified NC machine tool for each predetermined cycle.

More preferably, the NC machine tool is used for die machining.

As described above, in the present invention, the host computertransmits data for changing setup and NC data for machining for each ofthe NC machine tools to each of the high-speed data processing unitscorresponding to each of the NC machine tools. On the other hand, thehigh-speed data processing unit converts the data transmitted from thehost computer into NC data, and inputs the data to each of the NCmachine tools. Further, while the machining by the NC machine tools orthe operation for changing the setup is being executed, the datatransmitted from the host computer is temporarily stored in thehigh-speed data processing units. When the NC machine tool has beenprepared for receiving the transmitted data, the high-speed dataprocessing unit inputs the transmitted data, which has been convertedinto NC data, to each of the NC machine tools.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram schematically showing a DNC system for diemachining according to one embodiment of the present invention;

FIG. 2 is a flowchart schematically showing data transfer processing bythe host computer applied in the DNC system for die machining of thesame embodiment; and

FIG. 3 is a flowchart schematically showing transmitted data conversionprocessing by a high-speed data processing unit included in the DNCsystem for die machining of the same embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be explained below withreference to the drawings. FIG. 1 is a block diagram schematicallyshowing a Direct Numerical Control (hereinafter referred to as DNC)system for die machining according to one embodiment of the presentinvention. Each of reference numerals 6a to 6d denotes an NC machinetool such as an NC milling cutter, NC grinder, or the like. Further,these NC machine tools 6a to 6d are equipped with machine tool bodies 5ato 5d, and NC units 4a to 4d for controlling a drive of each of machinetool bodies, respectively.

The host computer 1 generally controlling these NC machine tools 6a to6d includes a microprocessor which functions as an arithmetic unit,memories such as ROM/RAM which store programs, set data, a manualcontrol panel for inputting data, and a CRT display as a displayingmeans. These memories previously store various machining data comprisingmachine tool numbers for designating NC machine tools 6a to 6d and NCdata for executing different machining operations, and setup dataincluding tool numbers required for instructing the change of setup orthe like.

Each of high-speed data processing units 3a to 3d, correspondinglylocated in the respective NC machine tools 6a to 6d, is connected to anNC coupling unit which constitutes an interface of the host computer 1through a Local Area Network (hereinafter referred to as LAN) 2 as datatransmission paths. The NC units 4a to 4d of the NC machine tools 6a to6d are connected to the high-speed data processing units 3a to 3d,respectively. The respective high-speed data processing units 3a to 3dinclude a microprocessor, as an arithmetic unit, and memories such asROM for storing control programs, RAM for temporarily storing data, orthe like. The NC units 4a to 4d also include a microprocessor as anarithmetic unit, ROM for storing control programs, RAM as memory forstoring NC data, or the like. Rotation of a spindle, a feed of an axis,and the like of the respective machine tool bodies 5a to 5d arecontrolled in accordance with NC data stored in the NC data memory.

Referring to flowcharts shown in FIGS. 2 and 3, processing operations ofthe host computer and the high-speed processing units 3a to 3d in theDNC system according to the present embodiment will be described below.FIG. 2 is a flowchart schematically showing "data transfer processing"for specifying machine tool numbers of the NC machine tools 6a to 6d,and inputting them in the host computer 1, thus transmitting setup dataand machining data for each machine tool. This operation can beactivated by operating the manual operation panel of the host computer1, and selecting the item of "data transfer processing".

The host computer 1, which initiated the "data transfer processing",first calls all of the previously registered machine tool numberscorresponding to each of NC machine tools 6a to 6d, out of memoryincluded in the host computer 1, and displays them on a screen of theCRT display. After the prompt requesting the selection of machine toolnumbers is displayed (step S1), the computer waits until the operatorselects a desired machine tool number by using the operator controlpanel (steps S2 and S3). Subsequently, when the selection of the desiredmachine tool number by the operator is detected, the host computer 1temporarily stores the machine tool number selected by the operator, anddisplays the prompt requesting an input of the setup data from theoperator on the CRT display (step S4). Further, the computer waits foran input of tool numbers or the like required for changing a setup toexecute a machining operation (steps S5 and S6). When the input of thesetup data is completed, the computer 1 refers to the machine toolnumber selected in step S2, and specifies the NC machine toolcorresponding to the selected machine tool number, for example, thehigh-speed data processing unit 3a included in the NC machine tool 6a,thus transmitting not only the tool numbers but also the other necessarysetup data inputted at the present process (step S7). The setup datadoes not directly indicate cutting profile, tool path, or the like forthe machining, but show, for example, the tool number corresponding to atool to be mounted for the next machining, or the like. Thus, the setupdata is different from NC data in format.

The host computer 1, which transmitted the setup data, further displaysa list of various machining data stored in memory of the host computer 1on the CRT display, and informs the operator of the machining datacapable of being selected (step S8), and waits until the machining datais selected by the operator through the operator control panel (steps S9and S10). When the selection by the operator is detected, the hostcomputer 1 reads the selected machining NC data out of memory includedin the computer 1, and specifies the NC machine tool corresponding tothe machine tool number selected in step S2, for example, the high-speeddata processing unit 3a included in the NC machine tool 6a so as totransmit the machining NC data (step S11), thus resetting the machinetool number temporarily stored in response to the processing of step S2.

When the host computer 1 transmits the setup data and machining data tothe high-speed data processing unit corresponding to the machine toolnumber selected in the present process, the computer 1 waits until a setending or continuing key of the operator control panel is operated (stepS12). If the set continuing key is operated, the sequence again returnsto step S1, and the same procedures as described above are repeatedlyexecuted, thereby transmitting a new setup data and machining data tothe high-speed data processing unit included in the NC machine toolcorresponding to a machine tool number newly selected by the operator.On the other hand, if the set ending key is operated, the "data transferprocessing" ends temporarily.

After completing the "data transfer processing" temporarily, when theoperator again selects the item of "data transfer processing" throughthe operator control panel of the host computer 1, the host computerrepeatedly executes the aforesaid operation, thereby transmitting newsetup data and machining data to each of the high-speed processing units3a to 3d.

Meanwhile, each of the high-speed data processing units 3a to 3drepeatedly executes "transmitted data conversion processing" as shown inFIG. 3 for each specified cycle, and waits for the data transmissionfrom the host computer 1.

When the high-speed data processing units 3a to 3d initiate the"transmitted data conversion process" for each specified cycle, each ofthese units first determines whether or not a termination specifyingflag is set in memory of the high-speed data processing unit, or whetheror not all of processing concerning the scheduled operation of NCmachine tool including the high-speed processing unit are completed(step T1). If the termination specifying flag is not set, each of theprocessing units waits until the setup data or machining data istransmitted from the host computer 1 (step T2). Sequentially, when thehigh-speed data processing units 3a to 3d detect the reception oftransmitted data, each of these units determines whether the transmitteddata is the setup data or the machining data (step T3). If thetransmitted data is the setup data, each of the processing unitsconverts the setup data such as tool number required for changing thesetup for machining into NC data fop numerical control (step T4), andtransmits the converted setup data to the NC unit which is connected tothe high-speed data processing unit (step T5). On the other hand, if thetransmitted data is the machining data composed of NC data, each of theprocessing units additionally transmits the machining data to the NCdata memory of the NC unit as it is (step T5). Further, if thetransmitted data from the host computer 1, which is detected in thepresent step, is the machining data, each of the processing unitsdetermines whether or not a scheduled operation terminating command isset to the last of the transmitted machining data group. If thescheduled operation terminating command is set, the terminationspecifying flag is set in memory of the high-speed data processing unit.Accordingly, the decision made in step T1 becomes false in a state inwhich the termination specifying flag is set, and the "transmitted dataconversion processing" is substantially non-executable.

According to the present embodiment, the setup data transmitted from thehost computer 1 is converted into NC data by means of the high-speeddata processing units 3a to 3d, and is thereafter inputted to each ofthe NC units 4a to 4d, so that neither the host computer 1 nor the NCunits 4a to 4d need to execute the operation for converting the setupdata, thereby reducing loads on both the host computer 1 and NC units 4ato 4d.

The DNC system for die machining according to the present embodiment isfurther capable of executing processing operations as described below.

In the case where the setup data concerning the whole schedule of eachof the NC machine tools 6a to 6d and the machining data cannot be storedsimultaneously in memory due to lack of capacity of the high-speed dataprocessing units 3a to 3d, each of the NC machine tools 6a to 6d isfirst individually selected pursuant to the aforesaid "data transferprocessing" (steps S1 to S3). The machining data for only one processand setup data for the next process in each schedule are set to the hostcomputer 1, and are then transmitted to the high-speed data processingunits 3a to 3d, thereby storing these data in memory (steps S4 to S11).Thereafter, such an operation is repeatedly executed (step S12), and themachining data for one process and setup data for the next process ofthe respective NC machine tools 6a to 6d are stored in memory of each ofthe high-speed data processing units 3a to 3d. In this case, in order totransmit the machining data for the first process in each schedule, thesetup data for initiating the first process and for initiating thesecond or next process are transmitted simultaneously. On the otherhand, each of the high-speed data processing units 3a to 3d detects thereception of the machining data for one process and the setup data forthe next process in the "transmitted data conversion process" (steps T1to T3), and then converts the transmitted setup data into NC data (stepT4), thus transmitting the converted setup data and the machining datato memory of each of the NC units 4a to 4d (step T5). The rotation ofspindle and a feed of each axis of the machine tool bodies 5a to 5d arecontrolled by the NC units 4a to 4d, thereby performing a desiredmachining. When the capacity of each memory for storing NC data of theNC units is not large enough, the high-speed data processing units 3a to3d temporarily store the setup data, which is transmitted from the hostcomputer and converted, and the machining data in each memory of theseprocessing units (a process in place of step T5). Thereafter, theseprocessing units detect availability of a free space in memory of eachof the NC units 4a to 4d in every other specified cycle, which istime-shared, and the machining data equivalent to the free space may besequentially transmitted, from each memory of the high-speed dataprocessing units 3a to 3d, to each memory of the NC units 4a to 4d.

In such a case, only machining data for one process and setup data forthe next process out of the whole schedule of the NC machine tools 6a to6d are stored in each memory of the high-speed data processing units 3ato 3d. However, in a step in which the machining for one process by theNC machine tools 6a to 6d has progressed to some extent, or in which themachining for one process has been completed to initiate the setupoperation for the next process, there is sufficiently large free spacein each memory of the high-speed data processing units 3a to 3d. Thisallows the followings: during execution of the machining for oneprocess, or of the setup operation for the next process, when the "datatransfer processing" by the host computer 1 is again executed, the nextmachining data for one process and setup data for initiating thefollowing process are set and transmitted to the high-speed dataprocessing units 3a to 3d. Accordingly, it is not necessary to interruptan operation of each of the NC machine tool 6a to 6d in order toexecuted the data transmission from the host computer 1, therebyeffectively operating each of the NC machine tools.

If each memory of the high-speed data processing units 3a to 3d hassufficient capacity, the setup data concerning the whole schedule ofeach of the NC machine tools 6a to 6d and the machining data can bestored simultaneously in each memory of the high-speed data processingunits 3a to 3d. In this case, each of the NC machine tools 6a to 6d isfirst individually selected pursuant to the aforesaid "data transferprocessing" (steps S1 to S3). The machining data for all processes andsetup data for all processes in each schedule, are set to the hostcomputer 1, and are then transmitted to the high-speed data processingunits 3a to 3d thus these data being stored in memory (steps S4 to S11).Thereafter, such an operation is repeatedly executed (step S12), and themachining data for the entire process and setup data for all processesof the respective NC machine tools 6a to 6d are stored in memory of eachof the high-speed data processing units 3a to 3d. On the other hand,each of the high-speed data processing units 3a to 3d detects thereception of the machining data for the entire process and the setupdata for the entire process in the "transmitted data conversionprocessing" (steps T1 to T3), and then converts the transmitted setupdata into NC data (step T4), thereby causing the converted setup datafor the entire process and the machining data for the entire process tobe stored in each memory of the high-speed data processing units 3a to3d (a process in place of step T5). Thereafter, these processing unitsdetect the presence of a free space in memory of each of the NC units 4ato 4d in every other specified cycle which is time-shared, and themachining data equivalent to the free space may sequentially betransmitted from each memory of the high-speed data processing units 3ato 3d to each memory of the NC units 4a to 4d. The rotation of spindleand a feed of each axis of the machine tool bodies 5a to 5d arecontrolled by the NC units 4a to 4d, thus sequentially performing themachining of the entire schedule in an on-line mode.

In this case, since the host computer 1 is merely utilized as set dataselecting means and input means, in order to execute the datatransmission from the host computer 1, it is not necessary to interruptan operation of each of the NC machine tools 6a to 6d, so that each ofthe NC machine tools can effectively be operated likewise.

As described above, the present invention provides a DNC system for diemachining, which includes a high-speed data processing unit for each ofNC machine tools installed between each of NC machine tools and the hostcomputer. The high-speed data processing unit converts the datatransmitted from the host computer into NC machine tools, so that thehost computer and NC machine tools need not convert the data to the NCdata, and load on the host computer and NC machine tool can be reduced.Further, even when machining data or the like from the host computer istransmitted to the high-speed data processing units while NC machinetools are in operation, the high-speed data processing unit cantemporarily store the machining data or the like, and continue themachining operation of NC machine tools, so that a plurality of NCmachine tools can smoothly and effectively be operated without beingdisturbed by the timing of data transmission between the host computerand NC machine tools.

We claim:
 1. A DNC system for controlling a plurality of NC machinetools connected to one host computer, comprising:a plurality ofhigh-speed data processing units provided for each of said plurality ofNC machine tools, respectively, each to distribute command informationtransmitted from said one host computer to each of said respective NCmachine tools; and data input means, connected to said host computer,for inputting a specified one of said plurality of NC machine tools andfor inputting set-up data for said specified NC machine tool, said hostcomputer then transmitting said set-up data, indicating a change ofset-up for machining, to one of the high-speed data processing unitscorresponding to the specified NC machine tool and transmitting NCmachining data, corresponding to said specified NC machine tool and readfrom a memory of said host computer, to said corresponding high-speeddata processing unit, said corresponding high-speed data processing unitfurther determining said transmitted data to be said set-up data andsaid NC machining data, respectively, converting said determined set-updata into NC set-up data for numerical control and transmitting saidconverted NC set-up data to an NC unit for the specified NC machinetool, and transmitting said determined NC machining data to the NC unitfor the specified NC machine tool as is.
 2. A DNC system according toclaim 1, wherein said plurality of high-speed data processing unitsconvert data not being of NC data format of the command informationtransmitted from said host computer into NC data, and input theconverted data to each of a plurality of NC units respectively connectedto said respective plurality of NC machine tools.
 3. A DNC systemaccording to claim 1, wherein said NC machine tools are used for diemachining.
 4. A DNC system for controlling a plurality of NC machinetools connected to one host computer, comprising:a plurality ofhigh-speed data processing units provided for each of said plurality ofNC machine tools, respectively, each to distribute command informationtransmitted from said one host computer to each of said respective NCmachine tools; and data input means, connected to said one hostcomputer, for inputting a specified one of said plurality of NC machinetools and for inputting set-up data for said specified NC machine tool,said host computer then setting and transmitting only NC machining data,read from a memory of said host computer and corresponding to saidspecified NC machine tool, for one process and said set-up data, forchanging a set-up for machining, for a next process in an operationschedule of the specified NC machine tool to a high-speed dataprocessing unit corresponding to the specified NC machine tool, saidcorresponding high-speed data processing unit further receiving andstoring the transmitted NC machining data for said one process and thetransmitted set-up data for the next process, and converting thetransmitted set-up data into NC set-up data and transmitting theconverted NC set-up data to an NC unit of the specified NC machine tooland transmitting the NC machining data to the NC unit of the specifiedNC machine tool.
 5. A DNC system according to claim 4, wherein saidcorresponding high-speed data processing unit further temporarily storesthe converted NC set-up data and the NC machining data in a memory ofsaid high-speed data processing unit, and then transmits the storedconverted NC set-up data and NC machining data to the NC unit of thespecified NC machine tool, in every predetermined cycle.
 6. A DNC systemaccording to claim 5, wherein while machining is being executed inaccordance with the NC machining data for the one process transmitted tothe specified NC machine tool or a setup operation for the next processis being executed based on the NC set-up data, the host computer setsmachining data for a subsequent next one process and data required forchanging a setup for initiating the subsequent next one process, andthen transmits these data to the high-speed data processing unit.
 7. ADNC system for controlling a plurality of NC machine tools connected toone host computer, comprising:a plurality of high-speed data processingunits provided for each of said plurality of NC machine tools,respectively, each to distribute command information transmitted fromsaid one host computer to each of said respective NC machine tools; anddata input means, connected to said host computer, for inputting aspecified one of said plurality of NC machine tools and for inputtingset-up data for said specified NC machine tool, said host computer thensetting and transmitting NC machining data, read from a memory of saidhost computer and corresponding to said specified NC machine tool, forall processes of an operation schedule to be covered by the specified NCmachine tool and transmitting the set-up data, for changing a set-up formachining, of said all process of said operation schedule, to ahigh-speed data processing unit corresponding to the specified NCmachine tool which stores the transmitted data in a memory, and whensaid corresponding high-speed data processing unit receives the NCmachining data and the set-up data for said all processes of saidoperation schedule, said corresponding high-speed data processing unitconverts the set-up data into NC set-up data and stores the converted NCset-up data in said memory, thereby sequentially transmitting the storedNC set-up data and NC machining data to a memory of an NC unit for thespecified NC machine tool, in every predetermined cycle.